Impact of the LPS from Cyanobacteria Brasilonema sp.on Lung Inflammation and Glucocorticoid Expression

Abstract

Abstract Inhaled glucocorticoids (GCs) are the first-line treatment for asthma. However, patients with asthma characterized by recruitment of neutrophils show poor sensitivity to GC therapy. A potential etiology of this GC-resistant asthma is aerosolized cyanobacterial lipopolysaccharide (LPS) from cyanobacterial blooms. Previously, we demonstrated that inhalation of LPS from Geitlerinema sp. of cyanobacteria induces neutrophilic lung infiltration in mice. Our current data shows that the LPS from another cyanobacteria, Brasilonema sp., also induces lung inflammation after inhalation. Flow cytometric data demonstrate that Brasilonema sp. LPS induces neutrophil infiltration and ELISA identified increases in pro-inflammatory cytokine levels in bronchoalveolar lung fluid after Brasilonema sp. LPS exposure. Furthermore, IHC data demonstrate that mice exposed to Brasilonema sp. LPS show an increased level of lung epithelial GCRβ, a glucocorticoid receptor (GR) analog that inhibits GC activity. Conversely, expression of GCRα, the GR isoform responsible for glucocorticoid sensitivity, remains unchanged. These data help to elucidate the mechanisms of Brasilonema sp. LPS-induced lung-inflammation and potential glucocorticoid resistance, while highlighting the importance of the toxin in promoting human disease near cyanobacterial blooms. This work is supported by the Kenneth A. Suarez Fellowship and Intramural Funds at Midwestern University.